Silica Dust and Concrete Grinding and Polishing: The Tragedy & the Beauty

Construction worker grinding concrete.A construction worker grinding the surface of concrete dry, and generating dangerous silica-bearing dust into the air. This hazard could be eliminated with wet grinding methods.

Grinding and polishing of concrete will release the dangerous silica-bearing dust in to air, exposing construction workers and others. Breathing the silica dust can result in dangerous, irreversible, untreatable diseases, including silicosis and lung cancer (that’s the tragedy). Controlling exposures to the silica dust will eliminate the potential for the disease to occur (that’s the beauty!).

Operations that release silica dust into the air (Photo 1) are strictly regulated by the US Occupational Safety and Health Administration (OSHA), and enforcement would include the changing of work practices to control the release of dust into air. Examples of changes of work practices would include grinding with water to suppress the dust, or the use of specialty dust filters on the grinders, and exhaust ventilation. Workers also need to be trained about the hazards of silica and the proper use of respirators, although respirators should not be the primary control action.

Even if little visible concrete dust is present in the air, the silica levels may exceed the OSHA permissible exposure limit. Dry polishing should be avoided unless exposure monitoring (air sampling) confirms that the vacuum and filtration systems are effective. Suppression of the dust with wet-methods is the age-old choice of control of silica-bearing dust. By controlling the release of the dust into the air, the workers exposure is minimized, and the dangerous, insidious disease can be prevented. OSHA inspectors will force the use of effective dust suppression work practices, and only allow personal respiratory protection as an interim method of control.

Microscopic view of typical concrete dust.Microscopic view of typical concrete dust, with fine-grained carbonate and rock fragments. The silica is “glass-like”, in the form of transparent, jagged, shard-like fragments (not unlike a broken window). Only the very smallest particles are respirable (<10 µm in diameter), and can be deposited into the deepest portions of the lungs. These fine particles of silica may not be visible in air during a concrete polishing operation.



Harry J. Beaulieu, PhD, CIH, CSP

President and Senior Scientist
Industrial Hygiene Resources



Benefits of Polished Concrete

Health Issues

LEED US Green Building Council

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